Ofcom clears 4G for maritime navigation

3,000+-tonne ships clear for transmission...

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Ofcom's investigation into the potential for 4G telephony to knock out maritime radar has concluded that it just won't happen, at least not in any significant way.

A technical examination (PDF, dull) carried out by the regulator concludes that even taking worst-case assumptions – that operators build 4G masts pointing directly out to sea – 4G transmissions would only impact radar within 500 metres or so, and even then not very much.

Most maritime radio is well clear of the upper 4G band, at 2.6GHz, as opposed to the lower 4G band which is busy knocking out TV transmissions. International agreements require all ships over 300 tonnes carry X-Band radar, which operates at 9.3-9.5GHz, but those of more than 3,000 tonnes can also carry S-Band radar which uses spectrum quite near the 4G band and thus worthy of examination.

But Ofcom's calculations put the absolute limit of a detectable signal at around two-and-a-half miles out to sea, with actual interference not being seen until the ship gets within 500 meters of the transmitter.

We'd hope that a 3,000-tonne ship hovering 500 meters from a land-based radio mast wouldn't be relying on S-Band radar, but even if it is, then there seems little to worry about as other countries have deployed transmitters without any complaints.

It's a small detail, but indicative of the broad range or applications that have to be checked out before Ofcom can start flogging off the 4G spectrum. ®